Electric heater for circulating fluids



July 18, 1933. FENDT AL 1,918,637

ELECTRIC HEATER FOR CIRCULATING FLUIDS Filed Nov. 24, 1930 2 Sheets-Sheet l July 18, 1933. E. FENDT ET AL ELECTRIC HEATER FOR CIRCULATING FLUIDS Filed Nov. 24, 1930 2 Sheets-Sheet 2 gmnlm;

Patented July q 18, 1933 UNITED STATES PATENT OFFICE EMIL FENDT AND cam, scnoao, or rRANKroR'r-on-rnn mnmnocnsr, exam; ASSIGNORS TO I. G. FARBENINDUSTRIE AKTmNcmELLscnAm', or rmxronr:

ON-TEE-MAIN, GERMANY I ELECTRIC HEATEB FOB CIRCULATING FLUIDS Application filed November 94, 1980, Serial No. 497,909, and in Germany November 29, 1828.

The present invention relates to an electric heater for heating circulating fluids of the kind in which a primary winding system is arranged round an iron jacket tube, and a short-circuited tubular coil system as a secondary circuit is wound coaxially round the primary system; the heater serves for heating gases and liquids.

An electric heater according to the invention is illustrated in the accompanying drawings wherein Fig. 1 is a sectional elevation of the device,

Fig. 2 is a sectional plan and Fig. 3-is a sectional elevation of one phase of a modification.

The electric heater according to the present invention consists of a primary winding system arranged round an iron jacket tube, and a short-circuited tubular coil system as a secondary circuit wound co-axially round the primary system. The internal cross section of the heat producing jacket tube carrying the coils is much greater, for instance, ten times, than that actually required for conducting the fluid to be heated. By the sudden alteration of the cross section in passing from the conducting pipes to the greatly enlarged jacket tubes the fluid to be heated is given a whirling motion in the latter; the heat exchange 1s thus promoted. By the insertion of a displacement block having a cor 0nding cross section into the part of the acket tube forming the heat-producing surface, the space required for the fluid to flow through the tube is narrowed in such a manner that the fluid to be heated passes through the space primary coil is such that it covers only so many secondary turns as are'necessary for the production of the required secondary active current. The remaining secondary turns act as a series resistance; heat is thus produced also in these turns. This form is of a particular advantage if for chemical reasons iron cannot be used for the part of the apparatus through which the fluid flows, necessitating the use of aluminium, for in; stance; in this case the actual resistance of the secondary part is increased. In this instance cast-iron cylinders carrying the heatresistant primary coils are fitted round the jacket tubes made of aluminium.

Experience has shown that it is unnecessary to close the magnetic circuit, because the ener of the primary ampere turns is compleltse y utilized by the massive iron inside the C01 In the accompanying drawin Fig. 1 shows asectional elevation of t e electric heater according to the invention. The 'fluid to be heated enters by the pi e H and is uni-' formly distributed into the t 'ree jacket tubes A by thestar-shaped connecting pipe 0,; the three branches are united in the socket G at tached to the distributing pipe E. From the latter spring the three tubular secondary .coils D which are connected at their other ends with the discharge outlet F. The changes in the velocity of the current of fluid have the special advantage of ensuring a thorough mixing of the fluid to be heated. In the jacket tubes A there are inserted displacement blocks J which cause the fluid to be heated to'pass atthe desired velocity along the walls heated by.the heat-resisting pr1 mary coils B. As the cross section of the jacket tube A is considerably greater than that of the connecting pipes C and C in the present case 12.5 timesit is possible to provide a large heating surface 'at'the primary part and to get on with a low number of turns of the primary coils B; thus a. consid erable quantity of copper is saved and the apparatus is simplified.

Fig, 2 is a sectional plan of the apparatus and particularly illustrates the arrangement ofthe jacket tubes and the tube coils.

Fig. 3 illustrates a form in which the acket tube may be of aluminum. The jacket tube 100 is surrounded b a cast-iron cylinder K havinga suitable thickness of wall. The cylinder the heat-producing jacket tube carrying the carries the heat-resistin primary coil *L, I coils is about 10 times larger than the internal which is surrounded by e secondary tubui cross section of the inlet pipe and in which 5 lar coil M. The length N of the primary coil a displacement block is arranged in the jacket is such that only so many turns of the tubular tube in :order to obtain the optimal velocity coils N are in the field as are required for the of the current of the fluid to be heated, the production of the secondary energy. The length and position of the displacement block displacement block J extends in the axial dibeing determined by the primary coil surrection of the jacket tube only so far as the rounding the jacket tube.

cast-iron hollow cylinder is surrounded by 2. In the electric heater for circulating the primary coil. fluids referred to in claim 1 the modification We claim: which consists in the primary coil extending 1. Electric heater for circulating fluids in the axial direction onlyover a part of the with a primary windin system fitted round turns of the coil.

an iron jacket tube an a short-circuited tu- I EMIL FENDT. bular coil system as a secondary circuit CARL SGHORQ wound co-axia lly roundthe primary system,

in which heater the internal-cross section of 

